EDITORIAL. 
507 
Among - the first who brought the value of their experiments 
in that same direction stands Chauveau, who took all the neces¬ 
sary precaution as to condition of health, of age, etc., and the 
results were positive, and prove that human tuberculosis may 
be communicated with difficulty, but it can, nevertheless. 
How to explain such different results, obtained by two great 
masters, is difficult, perhaps. 
But: “It is a well-known general law that the gradual 
adaptation of any parasite, in a media, inert or living, where it 
succeeds in developing, confers to him the aptitude to develop 
more easily in medias similar to the former. 
“ This is true for the bacillus of tuberculosis as for all other 
microbes. 
“ Every one knows how difficult it is to obtain a first culture 
of the bacillus of Koch on the most favorable medias. 
What is true of inert medias is still a fortiori more true 
of the living ones. 
“ Every one knows that the bacillus of rouget of swine 
grows with difficulty the first time in the rabbit’s organism ; to 
kill a rabbit surely, three or four must be inoculated, and death 
takes place only after four or five days, perhaps later; but if the 
microbe is made to pass from one rabbit to another its viru- 
lency becomes such that it will kill in a few hours ; and this 
bacillus, then, so virulent for the rabbit, has lost all its viru- 
lency for the pig, whence it comes ; it can be inoculated to pigs 
in large doses without killing him or even making him sick.” 
Nocard has besides shown how the bacillus of tuberculosis 
of man or of cattle, cultivated in the peritoneum of chickens, 
protected from phagocytary action by the use of collodion bags, 
would slowly acquire, little by little, the characters of the bacil¬ 
lus of aviary tuberculosis and become unable to kill guinea- 
pigs, or kill them only with lesions analogous to those of aviary 
tuberculosis. 
“ All those facts make me think that the results obtained 
by Prof. Koch proceed from causes of the same order,” says 
Nocard. 
